1. Field of the Invention
The present invention relates to a manufacturing method of GaAs metal semiconductor FET (Field Effect Transistor).
2. Description of the Prior Art
Generally, in order to dope high-density ions of impurity into the source/drain regions of GaAs compound semiconductor devices, ion-implantation methods using high energy have been widely used in the art of the present invention.
However, when the above-mentioned ion-implantation method is applied to the fabrication of a GaAs metal semiconductor device, since lots of impurity ions are injected into the source/drain regions during the process, a problem arises in damaging of ohmic contacts of metal electrodes.
Also, when the ion-implantation method is applied to the fabrication of metal semiconductor devices using a self-aligned gate, ohmic contacts of metal electrodes get damaged due to lots of impurity ions. Thus doping density can not be raised to its maximum, and therefore electrical resistance of the ohmic contacts is raised.
Typical method for forming ohmic contact on GaAs substrate and implanting impurity ions therethrough is disclosed in U.S. Pat. No. 4,540,446.